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4.26 CHAPTER FOUR

TABLE 4.12 Zebra Mussel Control

Treatment technique Remarks
Thermal 95 ° F (35 ° C) for 2 h
100% effective
Repeat 2 or 3 times per year
Oxidizing chemicals such as chlorine, bromine,
Chemical
potassium permanganate, ozone, carbon dioxide
Continue for 2 or 3 weeks or apply continuously
Nonoxidizing chemicals are effective and being developed
Coating of components Silicone-based coatings prevent attachment
80% successful
Copper/epoxy paints
Construction materials Copper
Brass
Galvanized steel
Mechanical Shovel or scrape
High-pressure hose
Sandblasting
Pipeline pigging
Other methods Ultrasound
High pressure
Electrocution
Oxygen depletion
UV light

5% of the laid eggs may actually survive, population increases can be huge in areas where
the environment is conducive to growth. The rapid reproduction rate can result in a ze-
bra mussel problem changing from nonexistent to a water supply emergency in a few
months.
A range of design techniques have been investigated as a means of controlling or pre-
venting zebra mussel infestation of water intake facilities, as shown in Table 4.12. The
most commonly used control method involves combinations of mechanical removal and
chemical treatment with chlorine and potassium permanganate applications to control re-
currence. Chemical treatment typically consists of a chemical feed point at the intake fa-
cility entrance to distribute treatment chemical across the full flow stream of the inlet.
Mechanical removal may be necessary to clean bar screens or pipelines infested by adult
mussels. If this is done, care should be exercised in planning the removal process. Dis-
posal of large volumes of shells and rotting mussel can be problematic, and the rotting
tissue has the potential of causing significant taste and odor problems in drinking water.
Control technologies using microorganisms to prevent attachment by and to kill zebra
mussels are being developed.
A second bivalve, the quagga mussel, has been discovered in the Great Lakes region.
This mussel is named after an extinct African relative to the zebra and appears very sim-
ilar to the zebra mussel to the untrained eye. The quagga tends to be slightly larger than
the zebra mussel. The quagga does not have a flat side, which prevents it from anchor-
ing to hard surfaces as tightly as zebra mussels. Both mussels have the ability to colonize
hard, rocky surfaces and soft sediments. The quagga mussel appears to tolerate higher-
salinity water than does the zebra and appears to survive at greater water depths. The
quagga mussel is another problematic aquatic species that may need to be considered when
one is designing an intake system.